Wessex Institute of Technology 2002 Advance Conference Information
2002; Elsevier BV; Volume: 89; Issue: 1 Linguagem: Inglês
10.1006/enrs.2002.4376
ISSN1096-0953
Tópico(s)Dental materials and restorations
ResumoIt has been postulated that phosphophoryn (PP) molecules bind specifically to type I collagen fibrils as the key event in inducing matrix mineralization in dentin. The nature and specificity of the collagen molecule–PP interaction has been examined by rotary shadowing–electron microscopy of mixtures of native, monomeric lathyritic rat skin collagen and purified rat incisor PP. An antibody to the amino-telopeptide of the collagen α1(I)-chain was used to determine the N-terminal end of the collagen molecules. Solutions of collagen and PP in 0.01 M ammonium formate (+/− antibody) were mixed and spread in 70% glycerol–30% 0.01 M ammonium formate on freshly cleaved mica surfaces using the sandwich technique. After rotary shadowing with Pt and backcoating with a carbon film, the spreads were viewed in a JEOL 1200EX TEM. The PP appeared as 15-nm diameter globules, the collagen as semi-flexible 270 nm filaments. At neutral pH and low PP/collagen mixing ratios, a single interaction site was evident, centered at approximately 210 nm from the N-terminus. The binding interaction induced a local conformational change in the collagen, bending the molecule and reducing its effective length. The sequence within the collagen–PP-binding domain has a net-positive charge but contains both positively and negatively charged groups.
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